Simulations of thermal conductance across tilt grain boundaries in graphene

Non-equilibrium molecular dynamics (MD) method was performed to simulate the thermal transportation process in graphene nanoribbons (GNRs). A convenient way was conceived to introduce tilt grain boundaries (GBs) into the graphene lattice by repetitive removing C atom rows along certain directions. Comprehensive MD simulations reveal that larger-angle GBs are effective thermal barriers and substantially reduce the average thermal conductivity of GNRs. The GB thermal conductivity is 10W center dot m(-1)center dot K-1 for a bicrystal GNR with amisorientation of 21.8A degrees, which is 97% less than that of a prefect GNR with the same size. The total thermal resistance has a monotonic dependence on the density of the 5-7 defects along the GBs. A theoretical model is proposed to capture this relation and resolve the contributions by both the reduction in the phonon mean free path and the defect-induced thermal resistance.